An electrohydrodynamic jet printing device and method applicable to printing on the inner and outer surfaces of a circumference

Abstract

The present invention belongs to the technical field related to inkjet printing devices, and discloses an electrohydrodynamic jet printing device and method applicable to printing on the inner and outer surfaces of a circumference. The device includes a three-jaw chuck, a nozzle, a linear push rod, a linear slide table, a piston, a top cover body, and a connecting shell that are connected in sequence. The three-jaw chuck is used for clamping a circumferential sample and driving the circumferential sample to rotate. One end of the linear push rod is connected to the linear slide table, and the other end is connected to the end of the connecting shell away from the piston. The nozzle is in an L shape, and one end of the nozzle is arranged inside the piston and connected to an ink supply pipe. The linear push rod is used for driving the nozzle to move along the axial direction of the circumferential sample, and the linear slide table is used for driving the nozzle to move vertically through the linear push rod, the connecting shell, the top cover body, the piston, and the ink supply pipe. The present invention can be simultaneously applicable to electrohydrodynamic jet printing on the inner and outer surfaces of a circumference.

Description

Technical Field

[0001] The present invention belongs to the technical field related to inkjet printing devices, and more specifically, relates to an electrohydrodynamic jet printing device and method suitable for printing on the inner and outer surfaces of a circumference. Background Art

[0002] Medical surgical robots are the main force in the field of minimally invasive surgery currently. By leveraging the advantages of robot intelligence, high precision, and rapid response, most diseases can be treated with the operating arms of surgical robots through small incisions. Robots need to rely on numerous sensors to sense physical information such as force, temperature, and pH value during the surgical process. However, traditional rigid sensors are difficult to integrate on the relatively small-scale operating arms of robots. The next-generation operating arms of surgical robots make full use of the inner and outer surfaces to achieve various functions such as sensing and processing, and new manufacturing methods are required to fabricate such micro-functional structures. Electrohydrodynamic jet printing technology is a high-precision non-contact additive manufacturing technology that can conformally fabricate circuit structures such as sensors on the substrate surface in an additive manner. Using electrohydrodynamic jet printing technology to fabricate conformal circuit structures on the inner and outer surfaces of the circumferential surgical robot operating arm can not only achieve the corresponding functions of the circuit structure but also solve the problem of low utilization rate of the assembly space. In this way, the circuit structure prepared on the inner surface of the surgical robot operating arm can isolate the interference of the external environment, have better stability, meet the requirements of real-time monitoring during surgical operations, and to a certain extent, the circuit structure printed on the inner surface has higher application value.

[0003] Traditional electrohydrodynamic jet printing processes are carried out on flat substrates. The basic principle is to fill the printing material into the nozzle, apply a high-voltage electric field between the nozzle and the substrate, and use the electric field force on the droplets at the nozzle to overcome the solution viscous force, surface tension, etc., so that the ink forms a stable focused jet with a diameter much smaller than the inner diameter of the nozzle at the nozzle, and the required micro-nano functional structures are fabricated on the substrate through this jet. However, when printing on circumferential surfaces such as the operating arms of surgical robots, since the printing height cannot be kept consistent, the electrohydrodynamic jet printing effect is unstable or even the deposition of printing materials cannot be carried out on large-curvature curved surfaces. Further, there are more restrictions in electrohydrodynamic jet printing on the inner surface of the circumference. For example, the narrow space cannot accommodate the common nozzle sizes, it is not easy for the fluid to achieve the optimal way of jetting perpendicular to the substrate, and it is difficult to construct an electric field between the nozzle and the substrate due to the insulating materials on the inner and outer surfaces of the surgical robot.

[0004] In view of the above problems, some new electrohydrodynamic jet printing devices have been proposed. Patents CN201710485691.2 and CN201811011385.6 respectively propose devices and methods for preparing functional structures by electrohydrodynamic jet printing on curved surfaces. However, the workbench of the device is designed based on large-area and small-curvature curved surfaces and lacks applicability to large-curvature surfaces such as micro-circular surfaces. Patent CN202210601841.2 proposes a device and method for preparing conformal sensitive structures on micro-circular curved surfaces, which solves the printing process for the outer circumferential surface, but the arrangement of the nozzles is not applicable to the narrow space of the inner surface. In current research, there is still a lack of electrohydrodynamic jet printing devices and methods for the inner circumferential surface. Summary of the Invention

[0005] In view of the above defects or improvement requirements of the prior art, the present invention provides an electrohydrodynamic jet printing device and method applicable to printing on both the inner and outer circumferential surfaces. It is proposed for the problem of preparing conformal circuit structures on the inner and outer surfaces of surgical robots, and can be simultaneously applicable to electrohydrodynamic jet printing on both the inner and outer circumferential surfaces, solving problems such as narrow inner surface space and difficulty in constructing an electric field on an insulating surface, and meeting the integrated application in the fields of curved surface electronics, flexible electronics, semiconductor manufacturing, etc. on medical surgical robots.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided an electrohydrodynamic jet printing device applicable to printing on both the inner and outer circumferential surfaces. The device includes a three-jaw chuck, a nozzle, a linear push rod, a linear slide table, a piston, a top cover body, and a connecting shell that are connected in sequence; the three-jaw chuck is used for clamping a circumferential sample and driving the circumferential sample to rotate; one end of the linear push rod is connected to the linear slide table, and the other end is connected to the end of the connecting shell away from the piston; the nozzle is in an L shape, one end of which is disposed in the piston and connected to an ink supply pipe.

[0007] The linear push rod is used for driving the nozzle to move along the axial direction of the circumferential sample, and the linear slide table is used for driving the nozzle to move vertically through the linear push rod, the connecting shell, the top cover body, the piston, and the ink supply pipe.

[0008] Furthermore, the piston, the top cover body, and the connecting shell form a receiving cavity for receiving the ink supply pipe; an air chamber is formed in the piston, and the air chamber is connected to a precision flow pump through a joint and an air pipe in sequence.

[0009] Furthermore, the device includes an adjustment cylinder that is movably disposed in the piston and partially received in the air chamber.

[0010] Further, one end of the adjustment cylinder contacts the ink supply tube of the ink supply module. By changing the air pressure in the air chamber, the up-and-down movement of the adjustment cylinder is controlled, so that the adjustment cylinder drives the ink supply tube to move up and down, and then drives the nozzle to move up and down.

[0011] Further, a driving wire is preset in the circumferential sample, and the driving wire is grounded; the nozzle is connected to a high-voltage power supply, so that an electric field is formed between the driving wire and the nozzle part.

[0012] Further, the device further includes an observation camera and a positioning camera. The positioning camera is arranged on the end face of the three-jaw chuck facing the circumferential sample, and the observation camera is obliquely arranged in the receiving cavity.

[0013] Further, both the observation camera and the positioning camera are industrial-grade endoscope cameras.

[0014] Further, the device further includes a microprocessor, and the microprocessor is respectively connected to the linear push rod, the linear slide, the three-jaw chuck and the nozzle.

[0015] Further, the precision flow pump is also connected to the ink supply tube, and a reversing valve is connected behind it for switching between the ink supply tube and the air tube.

[0016] The present invention also provides a method suitable for printing on the inner and outer surfaces of a circumference. This method is carried out by using the electrohydrodynamic inkjet printing device suitable for printing on the inner and outer surfaces of a circumference as described above.

[0017] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the electrohydrodynamic inkjet printing device and method suitable for printing on the inner and outer surfaces of a circumference provided by the present invention mainly have the following beneficial effects:

[0018] 1. The device takes into account the usage scenarios of the inner and outer surfaces of the circumference, and uses the electrohydrodynamic inkjet printing process to prepare a conformal circuit structure on the inner and outer surfaces of the circumference. The high-resolution electrohydrodynamic inkjet printing process is combined with the functional structure printing of the inner and outer substrates of the circumference. At the same time, with the cooperation of the two degrees of freedom of rotation around the axis and translation along the axis, the path planning for the processing of the inner and outer surfaces of the circumference is carried out, and the patterned conformal printing of the functional structure can be realized on the inner and outer surfaces of the circumferential substrate through the built-in program.

[0019] 2. The present invention proposes an integrated nozzle for printing on the inner and outer surfaces of the operating wall of a surgical robot, which includes a printing module, a vision module, a power supply module and an ink supply module. The integration of the working modules of the circumferential electrohydrodynamic inkjet printing is realized, and the switching of the printing on the inner and outer surfaces of the circumferential operating arm of the surgical robot can be conveniently realized by simply adjusting the position of the integrated nozzle.

[0020] 3. The present invention designs an "L"-shaped electrohydrodynamic printing nozzle, which realizes flexible printing operations in the narrow space on the inner circumferential surface. Combining with the optimal configuration of the nozzle of electrohydrodynamic printing perpendicular to the substrate, it fully adapts to the narrow space on the inner circumferential surface. Driven by air flow, through the bending structure, the ink can be ejected vertically from the nozzle and deposited and stacked on the inner surface along the normal direction of the substrate.

[0021] 4. The present invention proposes to construct a high-voltage electric field by using a preset metal driving wire structure in the operating arm of a surgical robot, which solves the problem that it is difficult to construct an electric field on the insulating circumferential surface by traditional methods, and this method is applicable to printing on both the inner and outer white surfaces of the circumference.

[0022] 5. The present invention uses a micro-precision air pump to achieve precise adjustment of the printing height between the nozzle and the inner surface, and designs a nozzle adjustment structure. Using the principle of air pressure balance, by controlling the charging and discharging of air through a precision flow pump, the adjustment cylinder can be moved up and down, and then the height of the nozzle relative to the inner surface can be adjusted, which solves the problem that it is difficult to directly drive the nozzle to move due to the narrow space and facilitates the on-line adjustment of the printing height parameters.

[0023] 6. The present invention performs real-time observation on the integrated printing process based on binocular vision. The positioning camera is used to measure the printing height and is arranged perpendicular to the end face of the sample, aiming to ensure that the printing height parameters can be measured on-line. The observation camera is installed on the integrated nozzle head and can observe the printing process and the internal situation of the circular tube in real time. Both of them use an industrial endoscope system to integrate the camera and the light source, and can stretch freely in a narrow space. Description of the Drawings

[0024] Figure 1 is a usage state diagram when the electrospray printing device provided by the present invention, which is applicable to printing on the inner and outer circumferential surfaces, performs printing on the inner circumferential surface. The main part of the electrohydrodynamic printing is in the dotted box;

[0025] Figure 2 is Figure 1 the structural schematic diagram of the integrated nozzle head of the electrospray printing device applicable to printing on the inner and outer circumferential surfaces in

[0026] Figure 3 is Figure 1 the schematic diagram of the construction principle of the electrohydrodynamic printing electric field of the electrohydrodynamic printing device applicable to printing on the inner and outer circumferential surfaces in

[0027] Figure 4 is Figure 1 the usage state diagram when the electrospray printing device applicable to printing on the inner and outer circumferential surfaces performs printing on the outer circumferential surface in

[0028] In all the drawings, the same reference numerals are used to denote the same elements or structures, where: 1 - integrated nozzle, 2 - circumferential sample, 3 - positioning camera, 4 - three-jaw chuck, 5 - servo motor, 6 - high-voltage power supply, 7 - precision flow pump, 8 - external gas supply pipe, 9 - linear slide, 10 - linear push rod, 11 - nozzle, 12 - observation camera, 13 - top cover body, 14 - ink supply pipe, 15 - gas pipe, 16 - joint, 17 - piston, 18 - adjustment cylinder, 21 - robotic manipulator, 22 - drive wire. Detailed implementation manners

[0029] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] Please refer to Figure 1 , Figure 2 , Figure 3 and Figure 4 , the present invention provides an electrohydrodynamic jet printing device suitable for printing on the inner and outer surfaces of a circumference. The device takes into account the printing requirements of the inner and outer surfaces of the robotic manipulator 21 of a surgical robot. In particular, printing on the inner surface of the circumference can prepare a conformal circuit structure on the inner surface of the manipulator, and various sensors further manufactured can monitor the operating state of the surgical robot in real time. At the same time, the inner surface structure avoids contact with the human body, making it more valuable for research and practical use.

[0031] Among them, the structure of the robotic manipulator 21 of the surgical robot can be simplified to a hollow cylinder. The device can be used to print a conformal circuit structure on the inner and outer surfaces of the manipulator, and then form the corresponding electronic component functions through post-processing. The assembled sensors can monitor the on-line state of the surgical robot. The pattern styles of the conformal circuits are rich. In addition to the serpentine line structure shown in the figure, there are also straight lines, corrugated lines, spiral lines and other structures.

[0032] This embodiment can print out the above various patterns by integrating the movement along two degrees of freedom of the circumference and the axis of the sample through a built-in path planning program, and through simple structural adjustment, the device can take into account the printing requirements of the inner and outer surfaces of the circumference. In comparison, the structure for printing on the inner surface of the circumference can avoid direct contact with the human body, making it more valuable for research and practical use.

[0033] The device includes a printing module, a vision module, an ink supply module, a power supply module, and a microprocessor. The microprocessor is respectively connected to the printing module, the vision module, the ink supply module, and the power supply module. The ink supply module is connected to the printing module. The printing module is the working end based on the principle of electrohydrodynamic jet printing, and is used for ejecting and stacking conductive materials on the surface of the circumferential sample 2 and adjusting the printing height parameters. The motion module is the working end based on path planning, and plans the printing path of the circuit structure through the rotation of the circumferential sample 2 and the translation of the integrated nozzle 1 of the device. The vision module is used for positioning the printing height and real-time observation of the printing process. The power supply module is used for applying a high-voltage electric field between the surface of the integrated nozzle 1 and the circumferential sample 2. The ink supply module is used for supplying printing materials. In this embodiment, considering the narrow space on the inner surface of the circumference, part of the structures of the printing module, the vision module, the ink supply module, and the power supply module are integrated on the integrated nozzle 1.

[0034] The printing module includes a connection housing, a nozzle 11, a top cover body 13, a piston 17, an adjustment cylinder 18, an air pipe 15, and a joint 16. The two ends of the top cover body 13 are respectively connected to the connection housing and the piston 17, and the other end of the connection housing is connected to the motion module. One end of the air pipe 15 is connected to the piston 17 through the joint 16, and the other end is connected to the ink supply module. The adjustment cylinder 18 is arranged on the piston 17, and is used for adjusting the distance between the nozzle 11 and the inner and outer surfaces of the circumferential sample 2.

[0035] The piston 17 is cylindrical, and an air chamber is formed therein. One end of the air chamber is connected to one end of the air pipe 15 through the joint 16 to ensure tightness. The other end of the air pipe 15 is connected to the ink supply module. The adjustment cylinder 18 is movably arranged in the piston 17, and part of it is received in the air chamber. One end of the adjustment cylinder 18 contacts the ink supply pipe 14 of the ink supply module, and the movement of the adjustment cylinder 18 is controlled by changing the air pressure in the air chamber, so that the adjustment cylinder 18 drives the ink supply pipe 14 to move up and down.

[0036] The top cover body 13 is conical, and its large end and small end are respectively connected to the piston 17 and one end of the connection housing. The top cover body 13 is communicated with the piston 17 and the connection housing to form a receiving cavity, which is used for receiving the adjustment cylinder 18, the ink supply pipe 14, and the observation camera 12 of the vision module. The printing module is connected to the motion module through the other end of the connection housing.

[0037] The nozzle 11 is in an L-shaped bent shape. The printing material is supplied to the nozzle 11 by the self-inking module. After bending, the flow along the axial direction of the sample is converted into a flow perpendicular to the inner surface. Under the high voltage between the nozzle 11 and the surface of the circumferential sample 2 provided by the power supply module, according to the principle of electrohydrodynamic jet printing, the printing material jet will generate micro-droplets under the traction of the electric field force, spray perpendicularly to the inner surface and deposit on the inner surface. The effect of vertical inkjet has been proven to be the best, ensuring the stability of micro-droplet formation, spraying and deposition, and a printing structure with fewer defects can be obtained.

[0038] The motion module includes a three-jaw chuck 4, a servo motor 5, a linear slide 9 and a linear push rod 10. One end of the linear push rod 10 is connected to the linear slide 9, and the other end is connected to one end of the connecting housing. One end of the three-jaw chuck 4 is connected to the servo motor 5, which is used to clamp the circumferential sample 2 and provide it with rotational motion around the axis. The linear push rod 10 is used to drive the nozzle 11 to move horizontally along the central axis of the circumferential sample 2, and the linear slide 9 drives the nozzle 11 to move up and down through the linear push rod 10. Among them, the geometric model is decomposed into two-degree-of-freedom motor motions through a built-in path planning program, so as to print various patterns such as straight lines, serpentine lines, wavy lines, spiral lines, etc., enriching the structural and functional diversity of the conformal circuit.

[0039] The vision module includes an observation camera 12 and a positioning camera 3. Both the observation camera 12 and the positioning camera 3 are industrial-grade endoscope cameras with their own light sources, and the images captured by the cameras can be displayed and switched on the terminal of the device. The positioning camera 3 is arranged on the three-jaw chuck 4, and its central axis coincides with the central axis of the three-jaw chuck 4. The positioning camera 3 is perpendicular to the end face of the circumferential sample 2, and an adjustment rod is built in to adjust the focal length. The relative position between the nozzle 11 and the inner surface of the circumferential sample 2 can be clearly observed at this position, and the printing height parameter of the nozzle 11 is determined in turn, which is used as a reference for the adjustment of the nozzle 11.

[0040] The observation camera 12 is arranged in the piston 17 through a wedge block and moves together with the nozzle 11. The inclined installation of the observation camera 12 on the piston 17 can ensure that the camera focal length and field of view can clearly see the nozzle 11 and observe the printing process in real time.

[0041] The ink supply module includes a precision flow pump 7, an external air supply pipe 8 and an ink supply pipe 14. Two ends of the external air supply pipe 8 are respectively connected to the precision flow pump 7 and one end of the mold supply pipe away from the nozzle 11. A reversing valve is connected after the precision flow pump 7 to convert the air path corresponding to ink supply and the height adjustment of the nozzle 11. The printing material is pre-filled into the nozzle. When printing, the ink supply air path is opened, and the ink liquid is driven by gas to increase the flow rate ejected from the nozzle 11, which is used to print a circuit structure with a thicker line width. The flow rate can also be adjusted on the terminal of the precision flow pump 7 through the microprocessor.

[0042] Wherein, when inflating the air chamber, the adjustment cylinder 18 moves upward under the action of gas pressure until it is balanced with the external air pressure. When exhausting the air chamber, the movement direction of the adjustment cylinder 18 is opposite. By adjusting the movement of the adjustment cylinder 18, the height change of the nozzle 11 can be controlled, and the precision flow pump 7 is controlled by the microprocessor to ensure the adjustment accuracy and fast response of the printing height.

[0043] The power supply module includes a driving wire 22 and a high-voltage power supply 6. The high-voltage power supply 6 is connected to the nozzle 11. The driving wire 22 is arranged inside the circumferential sample 2 and is grounded. In this embodiment, when the circumferential sample 2 is the operating arm 21 of the surgical robot, the driving wire 22 is a preset structure inside the circumferential sample 2. Among them, a copper wire is fixed inside the hollow tube of the nozzle 11 during manufacturing and a lead wire is led out. The driving wire 22 is made of metal and is an integrated structure of the operating arm 21 of the surgical robot. The pitching and deflection of the operating arm are controlled by the stretching and contraction of the wire. The traditional method of constructing an electric field is to apply a voltage between the nozzle 11 and the substrate, but the inner surface of the operating arm 21 of the surgical robot is not necessarily a conductor, and this method may not be applicable. Instead, in this embodiment, a metal conducting wire is used to ground, the wire inside the nozzle 11 is powered on, and a high voltage is formed between the nozzle 11 and the inner surface of the operating arm 21 of the surgical robot to construct the external electric field conditions for electrohydrodynamic printing. The high-voltage power supply 6 is controlled by the microprocessor, and the power supply voltage can be adjusted on the terminal to control the parameters of the printing state.

[0044] The present invention also provides a method suitable for printing on the inner and outer surfaces of a circumference. This method uses the electrohydrodynamic printing device suitable for printing on the inner and outer surfaces of a circumference as described above, and mainly includes the following steps:

[0045] S1, Prepare the printing material, pre-fill the printing material into the nozzle 11, and install the nozzle 11 on the ink supply pipe 14.

[0046] S2. Surface modification of the circumferential sample 2 such as the operating arm 21 of the surgical robot is performed by means of oxygen plasma, so that a large number of active molecules carrying charges are deposited on the surface of the sample, providing a more effective traction effect on the droplets by the electric field between the nozzle 11 and the surface of the circumferential sample 2 during subsequent electrohydrodynamic printing, and realizing high-precision deposition of the printing material.

[0047] S3. The circumferential sample 2 is fixed on the driving shaft of the servo motor 5 through the self-centering action of the three-jaw chuck 4, and the integrated nozzle 1 is moved to the printing starting point by the linear push rod 10.

[0048] S4. The positioning camera 3 and the observation camera 12 are turned on, the air pipe is connected, and the printing height is measured according to the image taken by the positioning camera 3 and adjusted to an appropriate value.

[0049] S5. The ink supply air pipe is connected, the high-voltage power supply 6 is connected, and the program is started to perform electrohydrodynamic printing according to the built-in pattern to obtain a conformal circuit pattern.

[0050] S6. The printed circumferential sample 2 is subjected to post-heating treatment, and the solvent in the ink is evaporated by local high temperature to leave the functional material, obtaining a conformal circuit structure with certain functions.

[0051] When printing on the outer circumferential surface, the linear slide 9 drives the linear push rod 10 to move upward and places the integrated nozzle 1 above the outer surface of the circumferential sample 2. In terms of path planning, the difference between inner and outer surface printing only lies in the rotational direction of the circumference, and other processes are basically the same. The device provided in this embodiment can satisfy printing on both the inner and outer circumferential surfaces, expanding the scope of use and value.

[0052] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An electrohydrodynamic inkjet printing device applicable to printing on the inner and outer surfaces of a circumference, characterized in that: The device includes a three-jaw chuck, a nozzle, a linear push rod, a linear slide table, a piston, a top cover body and a connecting shell which are connected in sequence; the three-jaw chuck is used for clamping a circumferential sample and driving the circumferential sample to rotate; one end of the linear push rod is connected to the linear slide table, and the other end is connected to the end of the connecting shell away from the piston; the nozzle is L-shaped, one end of which is arranged in the piston and connected to an ink supply pipe; The linear push rod is used for driving the nozzle to move along the axial direction of the circumferential sample, and the linear slide table is used for driving the nozzle to move vertically through the linear push rod, the connecting shell, the top cover body, the piston and the ink supply pipe; a driving wire is preset in the circumferential sample, and the driving wire is grounded; the nozzle is connected to a high-voltage power supply, so that an electric field is formed between the driving wire and the nozzle.

2. The electrohydrodynamic inkjet printing device applicable to printing on the inner and outer circumferential surfaces as claimed in claim 1, wherein: The piston, the top cover body and the connecting shell form a receiving cavity, and the receiving cavity is used for receiving the ink supply pipe; an air chamber is formed in the piston, and the air chamber is connected to a precision flow pump through a joint and an air pipe in sequence.

3. The electrohydrodynamic inkjet printing device applicable to printing on the inner and outer surfaces of a circumference as described in claim 2, wherein: The device includes an adjustment cylinder, and the adjustment cylinder is movably arranged in the piston and partially received in the air chamber.

4. The electrohydrodynamic inkjet printing device applicable to printing on the inner and outer circumferential surfaces according to claim 3, wherein: One end of the adjustment cylinder contacts the ink supply pipe of the ink supply module, and the up and down movement of the adjustment cylinder is controlled by changing the air pressure in the air chamber, so that the adjustment cylinder drives the ink supply pipe to move up and down, and then drives the nozzle to move up and down.

5. The electrohydrodynamic inkjet printing device applicable to printing on the inner and outer surfaces of a circumference according to claim 2, wherein: The device further includes an observation camera and a positioning camera, the positioning camera is arranged on the end face of the three-jaw chuck facing the circumferential sample, and the observation camera is obliquely arranged in the receiving cavity.

6. The electrohydrodynamic inkjet printing device applicable to printing on the inner and outer circumferential surfaces as claimed in claim 5, wherein: Both the observation camera and the positioning camera are industrial-grade endoscope cameras.

7. The electrohydrodynamic inkjet printing device applicable to printing on the inner and outer circumferential surfaces as claimed in claim 2, wherein: The device further includes a microprocessor, and the microprocessor is respectively connected to the linear push rod, the linear slide table, the three-jaw chuck and the nozzle.

8. The electrohydrodynamic inkjet printing device applicable to printing on the inner and outer surfaces of a circumference according to claim 2, characterized in that: The precision flow pump is further connected to the ink supply pipe, and a reversing valve is connected behind it for switching between the ink supply pipe and the air pipe.

9. A method applicable to printing on the inner and outer surfaces of a circumference, characterized in that: This method is carried out by using the electrohydrodynamic inkjet printing device applicable to printing on the inner and outer surfaces of a circumference according to any one of claims 1-8.

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